All I can find is this one:-
http://www.peachparts.com/shopforum/showthread.php?t=142632
Here they killed the nut with a dremel... could work I suppose
Not the thread I remember.
I guess if you have an arc welder you could try to tack the captive nut in place - but I wouldn't fancy trying it - seems like a good way of getting arc eye if you don't have an automatic shading visor...
I've been searching on google using the following string:-
captive seat nut site:peachparts.com
This is way better than using the in built search function which in my opinion is total rubbish.